The purposed research will concentrate on the following objectives and methods: (a) Test cold-cure filled and unfilled adhesive systems formulated previously and containing blocked isocyanate functions for their dental materials properties. (b) Synthesize, purify and characterise new blocked isocyanate containing monoment and polymers based on HEMA (hydroxyethyl methacrylate) TDI (2,4-tolylene diisocyanate) adducts. (c) Study of the interaction of these blocked isocyanate functional materials with dentin and enamel utilizing x-ray photoelectron spectroscopy (ESCA) and scanning electron microscopy (SEM). (d) Cold-cure systems containing blocked isocyanate functions formulated previously and with the new materials developed in (b) will be tested for adhesion to dentin and enamel by destructive methods monitoring modes of failure with SEM. (e) Selection monomers and polymers will be submitted for toxicity testing. (f) Measurements of tensile properties of selected set adhesives by known methods.